The present invention is concerned with the field of power semiconductor technology. It relates to a semiconductor component, in particular a thyristor, and to a semiconductor device.
Gate Controlled Thyristors or GCTs such as GTOs are driven with particularly low inductance in many demanding applications (in this respect, see, for example, an article by P. Steiner, H. Grxc3xcning et al., xe2x80x9cSerienschaltung von GTO-Thyristoren fxc3xcr Frequenzumrichter hoher Leistungxe2x80x9d [Series connection of GTO thyristors for high-power frequency converters], ABB Technik 5/1996, pp. 14-20, in particular FIG. 5). For the low-inductance connection between the component and the drive circuit situated on a connection board, a housing with a coaxial gate connection was proposed in an earlier patent application (not a prior publication), said housing enabling a contact inductance of  less than 1 nH between the GCT and the connection board. In the proposal, contact is made with the cathode of the GCT via a plate which is separate from the GCT, said plate taking the form e.g. of a continuous baseplate of the gate unit. The mounting of the GCT becomes simple as a result:
the connection board of the gate unit is placed onto the baseplate with ring;
on top of this comes the gate connection of the GCT, the GCT being placed by its housing into the resulting well;
the multilayer arrangement comprising baseplate/ring, connection board and GCT gate connection is screwed together at various points using screws. The connections from board to gate and cathode of the GCT are thus produced.
Another, improved embodiment avoids the costly arrangement of large-area, close-tolerance and nickel-plated baseplate and ring by replacing both of them by a deep-drawn well. Production can be significantly simplified as a result.
However, both variants are affected by a thermal disadvantage: the plate of the cathode well lies between the cathode flange and the heat sink and thus forms a second, further junction for the heat which emanates from the GTC and must be dissipated. That leads to a significant ( greater than 5%) reduction in the overall system performance, particularly in systems in which efficient cooling is a matter of importance.
The object of the invention, therefore, is to provide a semiconductor component and a semiconductor device of the type mentioned at the beginning which do not have the disadvantages described and are distinguished by greatly improved heat transfer in particular together with a simple structure and easy mounting on the cathode side.
The object is achieved by means of a semiconductor component, in particular a thyristor, and by means of a semiconductor device.
The invention""s semiconductor element and the semiconductor device, comprising gate unit and semiconductor component, enable a low-inductance connection between gate unit and insulating housing of the semiconductor component. A well for making contact with the cathode is no longer necessary since an auxiliary cathode is arranged directly on the housing. This is achieved by virtue of the fact that, in the semiconductor component, both gate connection and an auxiliary cathode connection comprise a respective flange protruding from the insulation housing, which enclose a printed circuit board or connection board of the gate unit when the semiconductor component is mounted. The gate connection and the auxiliary cathode connection thus form a pair of rings which preferably lie parallel one above the other and between which the connection board reaches the housing of the thyristor when the thyristor is mounted. This makes it possible to realize low-inductance, annular connections in the form of protruding flanges between gate and/or cathode and the connection board. The cathode itself remains uninfluenced thereby and can be brought into direct contact with the heat sink without any thermal impairment.
The mounting can be simplified by special shaping of the printed circuit and/or semiconductor component. In a first embodiment, the printed circuit board is provided with a concave incision which can be pushed into the gap formed by the two flanges. In further embodiments, in order that the thyristor can receive the connection board between auxiliary cathode connection and gate connection in the course of mounting without any difficulty and without any intervention in the connection configuration, specific mounting means are provided on a mounting opening in the printed circuit board and on the connections of the thyristor.
A first preferred embodiment of the invention is distinguished by the fact that the means are designed in such a way that the thyristor can be inserted into the mounting opening with the housing axis oriented perpendicular to the connection board and can be brought into the connection position by rotation about the housing axis. In this embodiment, the mounting operation is particularly simple while the mounting means have to be configured in a comparatively complicated manner. Preferably, the auxiliary cathode connection and/or the gate connection are/is subdivided into a plurality of segments, which are arranged such that they are distributed over the circumference and are separated from one another by first cutouts, and the mounting opening comprises second cutouts in segment form, which are arranged such that they are distributed over the inner circumference and their number and dimensions correspond to those of the segments. In the course of mounting, the segments of the thyristor are inserted through the second cutouts, until the connection board lies between the connections, and the thyristor is then rotated until the segments are located above and/or below the regions between the second cutouts and can be connected there to the connection board.
A second preferred embodiment of the invention is characterized by the fact that the means are designed in such a way that the thyristor can be screwed into the mounting opening with the housing axis oriented in an inclined manner with respect to the connection board. In this embodiment, the mounting means are designed in a particularly simple manner while the mounting operation itself requires somewhat greater adroitness. Preferably, the auxiliary cathode connection and/or the gate connection have/has at least one first cutout in segment or slot form on its circumference, and the mounting opening has at least one second cutout in segment or slot form on its inner circumference.
When a cutout in segment or slot form is used, it is advantageous that the connection board has merely a small interruption. This optimizes the gate current gradient.
The mounting means (segments and cutouts) may be present on the auxiliary cathode connection alone, on the gate connection alone, or on both connections. In the first case, the thyristor must be inserted (from above) with the cathode side first into the mounting opening. In the second case, the thyristor must be inserted (from below) with the anode side first into the mounting opening. In the third and last case, the insertion can be effected optionally from either of the two sides.
In general, such semiconductor devices comprising a respective gate unit with a semiconductor component arranged therein are inserted in a manner stacked one above the other. In the case of the semiconductor device according to the invention, it is advantageous that if a semiconductor component exhibits a defect, the entire stack does not have to be taken apart in order to exchange the defective element.